Time series profiles of salinity and temperature of the upper layers of the ocean are useful for the study of various ocean conditions such as the variation of ocean currents. Various types of oceanographic profilers have been used or proposed to measure ocean parameters at different depths.
A number of prior profilers involve moving the sensing instrument up and down along a moored line. Many of these prior devices operate by changing the buoyancy for each cycle of operation. An example of such a device is disclosed it, U.S. Pat. No. 3,927,562 which uses a plurality of gas generators wherein one gas generator is utilized to vary buoyancy for each cycle of ascent and descent.
One of the difficulties with present profilers is that considerable stored energy, in the profiler is required to repeatedly change buoyancy, or otherwise raise and lower the instrument, over many cycles of operation.
For the ocean current variation studies referred to above, it would be desirable to have a high resolution oceanographic profiler that can operate unattended for long periods of time, such as two years or longer, and be capable of daily operation to a depth of 2,000 m.